Thermoplastic elastomers (TPE) have rubber elasticity like vulcanizable rubber at room temperature yet also have properties intermediate rubber and plastic, i.e., exhibit properties of both vulcanizable rubber and plastic materials. Thermoplastic elastomers also can be injection-molded like a plastic material at high temperatures.
Due to these properties, thermoplastic elastomers can be used in various products that require resilience, such as sports equipment, food packaging, medical equipment, the exterior of portable IT devices, and home appliances, among others. In addition, because products formed of thermoplastic elastomers can be injection molded (in contrast to vulcanizable rubber), manufacturing times can be shortened. Further, products formed of thermoplastic elastomers can be recycled, also in contrast to vulcanizable rubber, and thus can be environmentally advantageous.
However, thermoplastic elastomers can have poor physical properties (such as elongation permanent set) at high temperatures and can have poor surface hardness (of 50A shore A) as compared to vulcanizable rubber products. This can limit the products in which thermoplastic elastomers can be used.
In order to overcome these limitations, thermoplastic elastomers have been alloyed with other resins. However, the thermoplastic elastomer still does not satisfy desired thermal properties at high temperatures and further can lose surface flexibility, which is an inherent advantage of TPEs.
US Patent Publication No. 2005/0288393 discloses a thermoplastic elastomer composition including thermoplastic resin, block copolymer, core-shell copolymer, and oil. However, the composition is not suitable for use for electric and electronic parts, in particular, a diaphragm for a washing machine, because the surface hardness (shore A) exceeds 70.
US Patent Publication 2004/0151933 discloses a thermoplastic elastomer composition including thermoplastic resin, rubber elastomer, saturated elastomer, and oil. The thermoplastic elastomer, however, cannot maintain a surface hardness of 50A (shore A) and its uses are also limited.